Weak electrolytes are substances which only partially dissociate into ions when dissolved in water. Weak acids such as acetic acid, found in vinegar, and weak bases such as ammonia, found in cleaning products, are examples of weak electrolytes.
Household chemicals are non-food chemicals that are commonly found and used in and around the average household. They are a type of consumer goods, designed particularly to assist cleaning, pest control and general hygiene purposes.
Food additives generally do not fall under this category, unless they have a use other than for human consumption. Cosmetics products can partially be counted in, because even though they are not for direct application to parts of the human body, they may contain artificial additives that have nothing to do with their dedicated purpose (e.g. preservatives and fragrances in hair spray). Additives in general (e.g. stabilizers and coloring found in washing powder and dishwasher detergents) make the classification of household chemicals more complex, especially in terms of health - some of these chemicals are irritants or potent allergens - and ecological effects.
Equilibrium chemistry is a concerned with systems in chemical equilibrium. The unifying principle is that the free energy of a system at equilibrium is the minimum possible, so that the slope of the free energy with respect to the reaction coordinate is zero. This principle, applied to mixtures at equilibrium provides a definition of an equilibrium constant. Applications include acid-base, host-guest, metal-complex, solubility, partition, chromatography and redox equilibria.
A chemical system is said to be in equilibrium when the quantities of the chemical entities involved do not and cannot change in time without the application of an external influence. In this sense a system in chemical equilibrium is in a stable state. The system at chemical equilibrium will be at a constant temperature, pressure (or volume) and composition. It will be insulated from exchange of heat with the surroundings, that is, it is a closed system. A change of temperature, pressure (or volume) constitutes an external influence and the equilibrium quantities will change as a result of such a change. If there is a possibility that the composition might change, but the rate of change is negligibly slow, the system is said to be in a metastable state. The equation of chemical equilibrium can be expressed symbolically as
A strong electrolyte is a solute that completely, or almost completely, ionizes or dissociates in a solution. These ions are good conductors of electric current in the solution.
Originally, a "strong electrolyte" was defined as a chemical that, when in aqueous solution, is a good conductor of electricity. With greater understanding of the properties of ions in solution its definition was replaced by the present one.
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of laws and concepts of physics. It applies the principles, practices and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics and dynamics, equilibrium.
Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a macroscopic or supra-molecular science, as the majority of the principles on which physical chemistry was founded, are concepts related to the bulk rather than on molecular/atomic structure alone. For example, chemical equilibrium, and colloids.